Liquid blending system



March 6, 1962 w, P. DooLEY ET AL LIQUID BLENDING SYSTEM Filed April 16,1958 United States Patent O 3,023,764 LIQUID BLENDING SYSTEM William P.Dooley, Wallingford, Pa., and Elvin L. Coe,

Nitro, W. Va., assignors to American Viscose Corporation, Philadelphia,Pa., a corporation of Delaware Filed Apr. 16, 1958, Ser. No. 728,848 9Claims. (Cl. 137-98) The present invention relates to a system foradding a constant proportion of a low viscosity liquid to a variablestream of high viscosity liquid, and in its more particular aspects theinvention is concerned with a system for adding a constant proportion ofdye, delustrant or the like to a stream of high viscosity yartificialfilament-forming solution such as viscose, acetate or the like.

While the invention will be described in particular reference to thespinning of viscose, it will be readily apparent that it is equallyadaptable to systems for spinning other artificial fibers and that inits broader aspects the invention is applicable to lluid distributionsystems generally. In the production of colored and/ or delusteredviscose rayon, it is essential in commercial practice to add the coloror delustrant to the main viscose stream at `a point which is fairlyclose to the spinning machine, and great difdculty has been experiencedin the past in producing a uniform product because of the diiculties inmaintaining a constant ratio between the added material and the mainviscose stream due to the fact that the volume of iow changes as partsof the spinning machine are started up and shut down, and also due tothe fact that the viscosity of the main viscose stream varies from timeto time.

It is accordingly the primary object of the present invention to providean improved system for injecting a constant proportion of an additiveinto a filament-forming spinning solution, the ilow of which isvariable.

A more general object of the invention is to provide an improved systemfor adding a constant proportion of a low viscosity liquid, which insome cases may be abrasive, to a high viscosity liquid when the volumeof flow of the high viscosity liquid is variable.

Other and further objects, features and advantages of the invention willbecome apparent as the description of a preferred embodiment thereofproceeds.

The FIGURE of the drawing is a diagrammatic representation of apreferred embodiment of the system.

The spinning solution or main viscose supply is contained in a tank 1()which may be located several hundred feet away from the spinning machine11. The spinning solution is conducted from the tank 10 through a mainconduit 12 to a blender or mixing apparatus 13, a portion of thesolution being diverted through a shunt line 14, presently to be moreparticularly described, which also discharges into the blender 13. Fromthe blender 13 the spinning solution passes through a short conduit 15to the spinning machine.

A prime mover 16, which may take the form of large capacity, lowprecision constant volume pump, feeds the spinning solution underpressure through the conduit 12. The prime mover 16 is driven from avariable speed drive 17, the speed of which is controlled by a suitableelectronic or hydraulic instrument 18 in accordance with the pressuresensed in the conduit 15 by a standard pressure sensing means 19 whichis connected through a line 20 to the instrument 18 which in turn isconnected by -a line 21 to the variable speed drive 17. It will beapparent that if one or more stations of the spinning machine are shutdown the pressure in the conduit 15 will rise, Whereas when additionalspinning stations are started up the prsure in the conduit 15 willdecrease. The instrument 18 is so .arranged that upon an increase inpressure in the conduit 15 variable speed drive 17 is operated todecrease Mice the speed of the pump 16 which thereby decreases the flowthrough the conduit 12 and, conversely, when the pressure in conduit 15decreases, the ow through conduit 12 is increased. r[hns the demand ofthe spinning machine controls the flow of bright viscose from the tank10 through the conduits 12 and 15.

A group of positive displacement pumps 22 and 23 are located in theshunt line 14 and between these pumps there is a blender 24 which willhereinafter be referred to as a preblender. Connected to the preblender24 by a conduit 25 is a supply tank 26 containing a solution or slurryof a delustrant, -dye or the like. This solution or slurry, which willin many instances contain an abrasive material, for example TiO2, ismaintained in the conduit 25 under controlled pressure by a pump 27which may be a non-precision pump such, for example, as a screw pump, aby-pass line 28 being provided to circulate back to the tank 26 any ofthe additive which does not pass into the preblender 24. A manuallyoperable needle valve 39 in the line 28 may be employed for regulatingthe amount of recirculation of the additive and therefore control thepressure at which the additive enters the preblender. The pump 23 has agreater demand or capacity than the pump 22 and this dilerence in demandof the two pumps is made up by the additive which is drawn into thepreblender. The additive containing the abrasive material is thusthoroughly mixed with a substantial volurne of non-abrasive spinningsolution in the preblender before entering the precision pump 23 and isthus so diluted that it may pass through pump 23 without producing unduewear on the pump.

The pumps 22 and 23 are driven from a common drive shaft 29 so that theratio of the speeds or the two pumps and consequently the relativedemands of said pumps remain constant even though the speeds are variedin the manner presently to be described. Of course there may be morethan one pump 22 and more than one pump 23 so long as the demand of thepumps following the preblender is greater than the demand of the pumpslocated upstream of the preblender.

For controlling the speeds of the pumps 22 and 23 in accordance with theamount of bright viscose passing through conduit 12, it is irstnecessary to provide means for determining the amount of said flow, andsince, as previously mentioned, the viscosity of the viscose changesfrom time to time, the ordinary means for measuring the flow ofNewtonian liquids are not suiiicient and it is therefore necessary toprovide a special means for measuring this ilow. Two factors areinvolved in this changing viscosity of the viscose. One is that theviscose solution in the tank 10 is made up in batches and all batchesare not v the same, and the other and more important factor is that theviscosity changes with the rate of shear, viscose being a thixotropicsubstance, and the varying speeds of the prime mover 16 of courseeffects changes in the rate of shear. Located in the conduit 12 upstreamfrom the shunt line 14 are a pair of pressure measuring cells 30 and 31.These cells are located fairly close together and would indicate thesame pressure were it not for the fact that a pump 32 is located in theconduit between the cells. The pump 32 need not be a precise meteringpump but when it is driven at the speeds necessary to maintain pressuresat the cells 30 and 31 substantially equal, itis doing no Work on theviscose and its speed can be used as an indication of the amount ofliquid owing through the conduit 12. The pump 32 is driven from theoutput of a variable speed drive 33 the torque output of which shouldremain at' a high level over the entire range'of speeds fromsubstantially zero speed to maximum. A suitable form of variable speeddrive 33 is known as the Specon drive which is manufactured by the SpeedControl Division of Fairchild Engine and Airplane Corporation. The inputof the variable speed drive may be driven by a motor 34. The pressuremeasuring cells 30 and 31 are connected toY a suitable standardinstrument 35 which in turn controls the output speed of the variablespeed drive 33 and regulates such output speed to whateverrextent isnecessary to balance the pressures in the cells 30 and 31. For example,when the pump 16 is slowed down due to a decrease in demand of thespinning machine, theY pressure at the cell 30 will drop below thepressure at cell 31 and the instrument 35 will thereupon cause thevariable speed drive 33 to slow down pump 32 in order to balance thepressures on opposite sides of the pump. Likewise, a speeding up of thepump 16 will cause the pressure at cell 30 to rise above the pressure atcell 31 and the pump 32 will thereupon be speeded up torebalance thesepressures. Y Y

The output shaft 36 of the variable speed drive 33 is directly connectedas by means of a chain drive 37 to a variable speed changer 38 for theaforementioned common drive shaft 29. Thus an increase in the volume offlow through the conduit 12, as indicated by the increased speed of thepump 32, necessary to maintain the pressures in the cells 30 and 31 thesame, will result in an increased speed of the common drive shaft 29since this drive shaft is mechanically connected to the output ofvariable speed drive 33 which drives the pump 32. Therefore, when thevolume of flow through the conduit 12 increases, an increased amount ofspinning solution is drawn through the shunt line 14 by the pump 22 andsince the pump 23 is also driven by the shaft 29 an increased amount ofadditive will be drawn through the line 25, the ratio of additive to thetotal ow through shunt 14 remaining constant as previously mentioned.

The ratio of the output speed of the variable speed changer 38 to itsinput speed is varied manually only when itis desired to change theratio between the amount of additive and the amount of solution owingthrough the conduit. In the case of adding a dye to a viscose spinningsolution, for example, the setting of variable speed drive 38 will bedetermined by the desired hue of the iilaments produced by the spinningmachine.

Since the present invention is concerned with the overall system andnotwith the particular instrumentation employed forrautomatically operatingthe various speed change devices nor with the details of the speedchange device per se, these have been illustratedY onlydiagrammatically. Likewise, the pumps, blenders, the spinning machine,etc., may all be of standard construction and therefore there is no needto describe these elements in detail.

Having thus described a preferred form of the inven# tion, what isclaimed is:

1. A system for supplying spinning solution to Ia spinning machinecomprising a main line for conveying spinning solution to a spinningmachine, a shunt in said main line, means for pumping a portion of thespinning solution owing in said main line through said shunt, means forintroducing an additive into said shunt, means for maintaining constantthe ratio between the amount of additive introduced into said shunt andthe amount of spinning solution owing through said shunt, means formaintaining constant the proportion between the amount of spinningsolution pumpedv through said shunt and the amount owing through saidmain line, and means controlled by the pressure in said main linedownstream from said shunt for Iautomatically `regulating the flow ofspinning solution through said main line.

2. The system according -to claim `1 wherein the means for introducingthe additive into the shunt'comprises a pair of tandemly arrangedpositive displacement pump means in said shunt, the downstream one ofsaid pump means having a greater capacity than the other, and anadditive line feeding into said shunt between said pair ofl pump means.

t 3. The system according to claim 2wherein said additive linedischarges directly into a blender located in said shunt.

4. The system according to claim 2 wherein the means controlled by thepressure in said main line downstream from said shunt comprises pressuresensing means in said main line at a point downstream from said shunt, aprime mover for the spinning solution located upstream from said shunt,and means controlled by said pressure sensing means for regulating saidprime mover inversely with the pressure sensed by said pressure sensingmeans.

5. The system according to claim 1 wherein the means controlled by thepressure in said main line downstream from said shunt comprises pressuresensing means in said main line at a point downstream from said shunt, aprime mover for the spinning solution located upstream from said shunt,and means controlled by said pressure sensing means for regulating saidprime mover in inverse proportion to the pressure sensed by saidpressure sensing means.

6. The system according to claim l wherein a blender is located in themain line at the point where said shunt rejoins said main line. v

7. A constant ratio liquid injection system comprising a source ofspinning solution, a main conduit for conveying spinning solution fromsaid source to a spinning machine, a prime mover for forcing spinningsolution through said conduit under pressure, a blender in said conduitdownstream from said prime mover, a shunt line leading from said mainconduit at a point upstream from said blender and discharging into saidblender, a pair of positive displacement pumps located in tandem in saidshunt line, means for introducing an additive under pressure into saidshunt line between said pumps, drive means for driving said pumps atconstantly related speeds, the downstream one of said pumps having agreater demand than the other, the difference in demand being made up bythe additive drawn into said shunt line, flow measuring means formeasuring the flow of spinning solution through said main conduit at apoint upstream from said shunt line, means operatively connecting saidflow measuring means to said drive means whereby said drive means isvaried in direct proportion to the flow of spinning solution throughsaid main conduit to thereby maintain constant the ratio of the owthrough said shunt to the flow through said main conduit, means formeasuring the pressure in said main conduit at a point downstream fromsaid blender, and means controlled by said last-mentioned means to varythe effective force of said prime mover in inverse proportion to thepressure.

8. A constant ratio liquid injection system comprising a source ofspinning solution; a main conduit for conveying spinning solution fromsaid source to a spinning machine, pressure supplying means for forcingspinning solution through said conduit under pressure, a blender in saidconduit downstream from said pressure supplying means, a secondaryconduit leading from said main conduit at a point between said pressuresupplying means and said blender, a metering pump means and a preblenderin said secondary conduit, means for. introducing an additive undercontrolled pressure to said preblender, a third conduit leading fromsaid preblender to said blender, metering pump means in said thirdconduit, said last-mentioned metering pump means having a greater demandthan said first-mentioned metering pump means whereby a predeterminedproportion of additive will be drawn into said preblender to satisfy thedemand of said second-mentioned metering pump means, a common drive forboth said metering pump means whereby the ratio of additive to spinningsolution passing through said third conduit will remain constantevenkwhen the volume of ow is varied, flow measuring means for measuringthe ow through said main conduit at a point upstream from said secondaryconduit, means controlled by said flow measuring means for varying thespeed of said common drive in proportion to the dow through said mainconduit whereby the ratio of ow through said secondary conduit to the owthrough said main conduit will remain constant, and means for Varyingthe effective force of said pressure supplying means in accordance Withthe pressure in said main conduit at a point downstream from saidblender.

9. A constant ratio liquid injection system comprising a source ofspinning solution, a main conduit for conveying spinning solution fromsaid source to a spinning machine, pressure supplying means for forcingspinning solution through said conduit under pressure, a blender in saidconduit downstream from said pressure supplying means, a secondaryconduit leading from said main conduit at a point between said pressuresupplying means and said blender, a metering pump means and a preblenderin said secondary conduit, means for introducing an additive underpressure to said preblender, a third conduit leading from saidpreblender to said blender, metering pump means in said third conduit,said lastmentioned metering pump means having a greater demand than saidrst-mentioned metering pump means whereby a predetermined proportion ofadditive will be drawn into said preblender to satisfy the demand ofsaid second mentioned metering pump means, a common drive for both saidmetering pump means whereby the ratio of additive to spinning solutionpassing through said third conduit will remain constant even when thevolume of flow is varied, ow measuring means for measuring the dowthrough said main conduit at a point upstream from said secondaryconduit, said dow measuring means comprising a pair of pressure sensingmeans in said main conduit for sensing the pressure in said conduit atclosely spaced points, pump means in said main conduit between saidpressure sensing means, means controlled by said pressure sensing meansfor regulating the speed of said pump means to produce the same pressureat the two pressure sensing means, said last-named means being connectedto said common drive for varying the speed of said common drive inproportion to the flow through said main conduit whereby the ratio offlow through said secondary conduit to the ilow through said mainconduit will remain constant, and means for varying the effective forceof said pressure supplying means in accordance with the pressure in saidmain conduit at a point downstream from said blender.

References Cited in the file of this patent UNTED STATES PATENTS1,496,377 Harvey Feb. 14, 1922 1,522,120 Halder Ian. 6, 1925 2,650,168Van Dijk et al Aug. 25, 1953 2,861,440 Bauer Aug. 6, 1957 2,837,102Bauer .lune 3, 1958 2,838,792 Keight et al June 17, 1958 2,929,731 DeVries Mar. 22, 1960

